The Diagnostic Value Of T-SPOT.TB Test For Tuberculosis Patients With Different Immune Status

Objective:To explore the difference of diagnostic efficacy of T-SPOT.TB in tuberculosis patients with different immune status.Methods:Clinical data of 1254 patients who were admitted to the Respiratory Department of the First Affiliated Hospital of Chongqing Medical University and underwent T-SPOT.TB examination between January 2019 and May 2020 were collected.A total of 492 patients(all patients group)were included in this retrospective study after non-conforming cases were excluded(including 189 patients with tuberculosis,303 patients with non-tuberculosis;169 patients in non-immunocompromised group and 323 patients in immunocompromised group).The data were analyzed by SPSS 22.0.The results of T-SPOT.TB were compared with the final diagnostic results,and the diagnostic efficiency was analyzed.Comparison of sample rate between groups was performed by chi-square test.Non-parametric Kappa test was used for consistency analysis.The ROC curve,AUC(area under the curve)were used to quantitatively evaluate the accuracy of diagnostic experiments,P<0.05was statistically significant.Results:1)The sensitivity and specificity of T-SPOT.TB for“all patients group”were 82.0%and 67.7%respectively.The positive pre dictive value was 61.3%,the negative predictive value was 85.8%,th e positive likelihood ratio was 2.54,the negative likelihood ratio wa s 0.27,the Youden index was 0.497 and the Kappa value was 0.467.2)Comparison of diagnostic efficacy indicators between groups:sen sitivity:non-immunocompromised patients group(88.7%)>immunocompr omised patients group(75.0%),P=0.015;Positive predictive value:non-i mmunocompromised patients group(81.9%)>immunocompromised pati ents group(46.6%),P=0.000;Positive likelihood ratio,Youden index,Kappa value:non-immunocompromised patients group(3.36,0.623,0.632)>immunocompromised patients group(2.19,0.408,0.345);Negative likelih ood ratio:non-immunocompromised patients(0.15)<immunocompromise d patients(0.39).Comparison of AUC:antigen-A:non-immunocompro mised group(0.870)>immunocompromised group(0.747),P<0.05;Anti gen-B:non-immunocompromised patients(0.841)>immunocompromised patients(0.787),P>0.05.3)Comparison of the median for the Spot-fo rming cells(SFCs)in hole-A(B)of the T-SPOT test between groups(unit:SFCS/2.5*10~5PBMCs):hole-A:non-immunocompromised patients grou p(21.0)>immunocompromised patients group(9.5),P=0.04;hole-B:no n-immunocompromised patients group(24.0)>immunocompromised patie nts group(15.0),P=0.034.4)The diagnostic sensitivity of T-SPOT.TB in patients with severe malnutrition/hypoproteinemia(65.6%)was low er than non-immunocompromised patients group(88.7%),P=0.003.The diagnostic specificity of T-SPOT.TB in patients complicated with"lun g cancer"(58.9%)was lower than non-immunocompromised patients group(73.6%),P=0.037.Conclusion:T-SPOT.TB has a good diagnostic value for TB patients without obvious immune impairment.Immunocompromise will lead to a significant decrease in T-SPOT diagnostic efficiency.So it is not recommended to carry out this test for TB screening in such patients.For patients who have undergone T-SPOT testing,test results,whether positive or negative,should be interpreted with caution.